Continuous oral pamidronate (APD), 1000 mg/day, was administered to 14 patients with rheumatoid arthritis. A control group of 13 patients with similar conditions received placebo under a double blind randomized study design. Periarticular erosion scores were significantly higher in the control group after 12 months treatment. This was attributed to a deterioration in this group rather than to an improvement in the APD treated one. By contrast, intraarticular narrowing score was not influenced by APD. Tolerance to oral APD was acceptable in all patients.